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PubMed1985

Enhancement of growth of aerobic and facultative bacteria in mixed infections with Bacteroides species.

The potential for mutual enhancement of growth of the Bacteroides fragilis and B. melaninogenicus groups and the aerobic and facultative organisms commonly isolated with them in mixed infections was evaluated. Enhancement was studied by measuring the relative increase in CFU of the two bacterial components inducing subcutaneous abscesses in mice. Of the 42 combinations between three isolates each of the B. fragilis and B. melaninogenicus groups and seven aerobic or facultative organisms, Bacteroides spp. were enhanced in only 8 and inhibited in 4. The aerobic and facultative bacteria were enhanced in 31 of the 42 combinations and depressed in 2. The organisms uniformly enhanced by all of the Bacteroides spp. were group A streptococci and Escherichia coli (all six instances), followed by Staphylococcus aureus and Klebsiella pneumoniae (five of six instances), Pseudomonas aeruginosa (four instances), group D streptococci (in three instances only by the B. fragilis group), and Haemophilus influenzae (one instance). It is apparent that the growth rate of facultative and aerobic bacteria is enhanced much more in mixed infections with Bacteroides spp. than that of their anaerobic counterparts.

Abscess↗
PubMed1990

Serum antibody responses in sheep after natural infection with Bacteroides nodosus.

Soluble outer membrane protein of Bacteroides nodosus extracted with potassium thiocyanate (KSCN) was employed as antigen in an enzyme linked immunosorbent assay (ELISA) to detect serum antibody in sheep naturally infected with a heterologous serogroup. Serum antibody responses in 55 sheep were monitored for 2 years and maximum levels were directly related to the severity of clinical foot lesions. Serum antibody levels rose 2 weeks after foot lesions developed and declined within several months of resolution of lesions. After the first footrot transmission period, antibody levels persisted significantly (P less than 0.001) longer in sheep that did not become affected in the next transmission period compared with sheep in which footrot recurred. Antibody response did not appear to result in resolution of foot lesions. ELISA using KSCN antigen gave similar results to whole cell ELISA where cells prepared from an homologous serogroup were used as antigen. Both these assays were more sensitive than ELISA in which heterologous whole cell antigen was used. Proteins extracted from the outer membrane of B. nodosus, which are known to be immunogenic in natural infection and common to different serogroups of B. nodosus, appear to be useful antigens for serological investigations of ovine footrot.

Animals↗
PubMed1983

[Studies of mixed anaerobic infections involving Bacteroides gingivalis].

The infectiousness of several combinations of bacteria containing Bacteroides gingivalis and other bacteria associated with periodontal diseases was evaluated by subcutaneous injection to guinea pigs. Among the seven mixtures studied, only one permitted the development of an infection easily transmissible to a second guinea pig; this bacterial mixture was composed of B. gingivalis, Fusobacterium nucleatum, Eubacterium saburreum, and Capnocytophaga ochracea (formerly Bacteroides ochraceus). Owing to its ability to synthesize many lytic enzymes and potentially cytotoxic products, B. gingivalis represented the most virulent species of the mixture. Results from in vitro studies suggest that the development of B. gingivalis in the infected animal depends on the growth of C. ochracea. Succinic acid produced in large amount by C. ochracea seems to be one of the growth factors used by B. gingivalis.

Animals↗
PubMed1987

Effect of immunization on experimental Bacteroides gingivalis infection in a murine model.

BALB/c mice were immunized with an invasive (A7A1-28) or noninvasive (381) Bacteroides gingivalis strain, Bacteroides intermedius, or Ringer solution. All immunized mice were subsequently challenged with the invasive B. gingivalis strain and examined for septicemia or secondary spread of the infection or both. Mice immunized with the invasive B. gingivalis strain localized the infection to the challenge site. Mice immunized with the noninvasive B. gingivalis strain, B. intermedius, or Ringer solution developed spreading infections. These data suggest that immunization with an invasive B. gingivalis strain can alter the course of subsequent infections.

Animals↗
PubMedDate not supplied

[Increase of anaerobic infections. Prevalence of Bacteroides. Apropos of 17 cases in abdominal surgery].

Seventeen cases of anaerobic infections in abdominal surgery are reported. Predominance of bacteroides is evident (9/17), especially bacteroides fragilis. The clinical manifestations of bacteroides infections are severe: 7 septicemias and 2 parietal infections, being the cause of the death in four patients. Bacteroides infection develops preferently in an old patient, with severe disease, in colic surgery especially in emergency. Bacteroides are characterized by their polyresistance to antibiotics: beta-lactamins, except carbenicillin, and aminosids. Metronidazole is a powerful bactericidal agent with a very low toxicity, particularly active in the treatment of these affections, as well as clindamycin. If oral route is impossible, chloramphenicol, I.V. tetracyclin, and above all carbenicillin are able to be used with success.

Abdomen↗
PubMed1975

Immune responses in eight patients infected with Bacteroides fragilis.

Sera from eight patients with either septicemia or pyothorax caused by Bacteroides fragilis were assayed for specific antibody by the agglutination, immunofluorescence, and agar gel diffusion techniques. Antibodies were detected in the sera of all eight patients by all three serological tests employed; titers as high as 1:160 and 1:320 were detected by the agglutination test and the immunofluorescence technique, respectively, and all patients had precipitating antibody. Failure of B. fragilis sub-species thetaiotaomicron to react with any heterologous antisera from the other seven patients infected with B. fragilis subspecies fragilis thetaiotaomicron was not serologically related to any of the other strains studied. Demonstration of an immune response to anaerobic infection supported the pathogenesis of anaerobes in infectious disease processes and indicated the possible diagnostic role that serological tests may serve in the diagnosis of anaerobic infections in humans.

Adult↗
PubMed2006

Integrated analysis of established and novel microbial and chemical methods for microbial source tracking.

Several microbes and chemicals have been considered as potential tracers to identify fecal sources in the environment. However, to date, no one approach has been shown to accurately identify the origins of fecal pollution in aquatic environments. In this multilaboratory study, different microbial and chemical indicators were analyzed in order to distinguish human fecal sources from nonhuman fecal sources using wastewaters and slurries from diverse geographical areas within Europe. Twenty-six parameters, which were later combined to form derived variables for statistical analyses, were obtained by performing methods that were achievable in all the participant laboratories: enumeration of fecal coliform bacteria, enterococci, clostridia, somatic coliphages, F-specific RNA phages, bacteriophages infecting Bacteroides fragilis RYC2056 and Bacteroides thetaiotaomicron GA17, and total and sorbitol-fermenting bifidobacteria; genotyping of F-specific RNA phages; biochemical phenotyping of fecal coliform bacteria and enterococci using miniaturized tests; specific detection of Bifidobacterium adolescentis and Bifidobacterium dentium; and measurement of four fecal sterols. A number of potentially useful source indicators were detected (bacteriophages infecting B. thetaiotaomicron, certain genotypes of F-specific bacteriophages, sorbitol-fermenting bifidobacteria, 24-ethylcoprostanol, and epycoprostanol), although no one source identifier alone provided 100% correct classification of the fecal source. Subsequently, 38 variables (both single and derived) were defined from the measured microbial and chemical parameters in order to find the best subset of variables to develop predictive models using the lowest possible number of measured parameters. To this end, several statistical or machine learning methods were evaluated and provided two successful predictive models based on just two variables, giving 100% correct classification: the ratio of the densities of somatic coliphages and phages infecting Bacteroides thetaiotaomicron to the density of somatic coliphages and the ratio of the densities of fecal coliform bacteria and phages infecting Bacteroides thetaiotaomicron to the density of fecal coliform bacteria. Other models with high rates of correct classification were developed, but in these cases, higher numbers of variables were required.

Animals↗
PubMed1981

Penicillin-resistant bacteroides melaninogenicus infection of the mandible.

Oral infections caused by gram-negative anaerobes are now recognized more frequently than in the past because of improved culturing techniques. A case of B melaninogenicus infection secondary to a fractured mandible, in which the organisms were both clinically resistant and insensitive on culture to penicillin, is presented. The organism was also shown to produce beta-lactamase. Clindamycin is appropriate dosage resulted in diarrhea, which precluded its continuation. Erythromycin therapy was curative in this case. In all cases in which the clinical course does not reflect the expected reasonable response to the appropriate antibiotic therapy, bacterial resistance to a drug should be considered, and laboratory testing for resistance and sensitivities should be performed.

Adult↗
PubMed1983

Immune response to Bacteroides fragilis in experimentally infected rabbits.

Experimental Bacteroides fragilis infections in rabbits were produced by injecting 10(9)-10(10) organisms into subcutaneously implanted steel-net tissue cages. Four B. fragilis type strains with divergent antigenic set-up were used. Viable counts in the cage contents reached a steady state at 10(7)-10(9) within 2-3 weeks. Bacteria coated with immunoglobulin were demonstrated in the pus. The antibody response in serum, followed with indirect immunofluorescence and detected within 7-10 days, was dominated by IgG; IgM antibodies were also involved but to a lesser degree. Serum antibody levels were not significantly influenced by infecting dose or strain, variations in viable counts or antibiotic therapy. Antibody response was directed against heat-stable as well as heat-labile antigens. Non-homogeneous staining, i.e. positive fluorescence of some of the cells in the preparation with the remaining cells negative, was found with heterologous and homologous cells and was found to be related to heat-labile antigen.

Animals↗
PubMed1977

Therapy for infections due to anaerobic bacteria: an overview.

Several classes of antimicrobial agents (e.g., penicillins, cephalosporins, tetracyclines, chloramphenicol, and clindamycin) are useful in treatment of infections due to anaerobic bacteria. However, certain anaerobic bacteria have shown a striking resistance to antimicrobial agents. In vitro susceptibility tests are useful for selection of optimal therapy. The choice of agent depends, to some extent, on the organisms responsible for the infection. Bacteroides fragilis is the most commonly encountered anaerobe, and it is also the most resistant to antimicrobial agents. Other factors influencing the selection of therapy include pharmacologic characteristics, degree of bactericidal activity, and toxicity. Proper therapy for anaerobic infections often requires intensive antimicrobial therapy for a prolonged period. Surgical intervention, including drainage of abscesses and excision of necrotic tissue, is important.

Anaerobiosis↗
PubMed1976

Bacteroides fragilis resistant to the administration of clindamycin.

The susceptibility of Bacteroides fragilis to the administration of clindamycin, and the efficacy of this agent in Bacteroides infections are well documented. Clindamycin-resistant strains of B. fragilis were isolated from two patients with bacteremia at two institutions. Clinically significant resistance to clindamycin therapy has not been noted previously in B. fragilis infections.

Aged↗
PubMed1995

Purification and characterization of a fibrinogen-degrading protease in Bacteroides fragilis strain YCH46.

A novel fibrinogenolytic protease was purified from Bacteroides fragilis strain YCH46. The protease was extracted from cells by ultrasonic treatment and was purified 425-fold with a recovery of 2.1% by sequential procedures using azocasein as a substrate. The purified protease showed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with an estimated molecular weight of 100 kDa, which was consistent with the value obtained by gel filtration, indicating a monomeric native structure. Its optimal pH, Km, and Vmax for azocasein were 7.5, 0.2%, and 286 U/min/mg, respectively. The protease activity was completely inhibited by addition of 1 mM Hg2+, Cu2+, Zn2+, diisopropyl fluorophosphate, N-ethylmaleimide or p-chloromercuribenzoate but not by the inhibitors of metalloprotease or aspartic protease, suggesting that the enzyme is a serine-thiol-like protease. The protease hydrolyzed azocasein, casein, fibrinogen, gelatin, and azocoll, but not bovine serum albumin, ovalbumin, fibrin, fibronectin, immunoglobulins, transferrin, hemoglobin or types I, III, and IV collagen. The enzyme also hydrolyzed the chromogenic substrates alanyl-alanine p-nitroanilide, L-valyl-alanine p-nitroanilide, alanyl-alanyl-valyl-alanine p-nitroanilide, and glycyl-proline p-nitroanilide, but was inert toward L-alanine p-nitroanilide, alanyl-alanyl-alanine p-nitroanilide, and N-alpha-benzoyl-DL-arginine p-nitroanilide. The protease completely hydrolyzed the alpha-chain of fibrinogen at 37 C within 10 hr and at the same time the time required for clotting of protease-treated fibrinogen by thrombin was prolonged. The fibrinogenolytic activity of a crude extract of B. fragilis was stronger than that of other species of the Bacteroides fragilis group tested: B. ovatus, B. distasonis, B. eggerthii, B. uniformis, and B. thetaiotaomicron. These results suggest that the fibrinogenolytic protease is an important biological factor in Bacteroides infection.

Amino Acid Sequence↗
PubMed1985

Characterization of the anomalous infection and nodulation of subterranean clover roots by Rhizobium leguminosarum 1020.

Anomalous nodulation of Trifolium subterraneum (subterranean clover) roots by Rhizobium leguminosarum 1020 was examined as a model of modified host-specificity in a Rhizobium-legume symbiosis. Consistent with previous reports, these nodules (i) appeared most often at sites of secondary root emergence, (ii) were ineffective in nitrogen fixation and (iii) were as numerous as nodules formed by an effective Rhizobium trifolii strain. R. leguminosarum 1020, grown on agar plates or in the clover root environment, did not bind the white clover lectin, trifoliin A. This strain did not attach in high numbers, and did not induce shepherd's crooks or infection threads, in subterranean clover root hairs. However, R. leguminosarum 1020 did cause branching, moderate curling and other deformations of root hairs. The bacteria probably entered the clover root through breaks in the epidermis at sites of lateral root emergence. The anomalous nodulation was inhibited by nitrate. Only trace amounts of leghaemoglobin were detected in the nodules by Western blot analysis. The nodules were of the meristematic type and initially contained well-developed infection, bacteroid and senescent zones. Infection threads were readily found in the infection zone of the nodule. However, the bacteroid-containing tissue senesced more rapidly than in the effective symbiosis between subterranean clover and R. trifolii 0403. This anomalous nodulation of subterranean clover by R. leguminosarum 1020 suggests a naturally-occurring alternative route of infection that allows Rhizobium to enlarge its host range.

Autoradiography↗